The present invention relates to a process for the manufacture of semi-finished polychrome composites from thin gage metal, and to a semi-finished article obtained by this process.
The polychrome composites are known in the manufacture of jewelry, precious metal and costume jewelry alike. Articles of this type are generally obtained by bonding together two or more layers of differently formulated, hence different color alloys, then machining through so as to expose the color of metal desired. Where a given article is to be embodied in green, red and white, for instance, layers of green, red and white material must first be bonded together; supposing the layer to have been disposed in this same order, with green at bottom, then a green motif on a white background will involve removal both of white metal and of red from all such parts of the surface area as the motif is to occupy.
Articles of this kind are often fashioned in gold, and the need therefore exists for recovery of the swarf which is machined away in order to expose the color beneath. Metal removed will never be the same color however, or rather, the same alloy, following machining; even in cases where the top layer only is machined so as to expose the second layer, a certain amount of the second layer must necessarily be removed, however thin. As a consequence, the swarf has to be refined in order to restore the purity of the precious metal.
The recovery of precious metals by refining poses no engineering problems, but the cost of the procedure is extremely high, and unavoidable because the abundant quantities of metal removed by machining simply cannot be disposed as waste.
Subsequent developments in the prior art methods aimed at obtaining color effects and/or particular types of embellishment, from layers of metal sandwiched together, have included shaping the layers in such a way as to interlock one with the next so that removal of the outermost layers will immediately expose the layer beneath. Significant amounts of metal still have to be removed from the outermost layers however, as well as a relatively smaller amount from at least one of the layers beneath, and the problem of mingled swarf remains unsolved. What is more, the semi-finished composite produced by this method is bound to be of thicker gage, and costs cannot therefore be reduced where precious metals are utilized.
One attempt at eliminating the particular problem of voluminous swarf involves utilizing first layers of metal with punched openings (signifying a considerable quantity of stock to be removed, even if the metal does remain substantially pure), and second layers, with edges either worked in relief or added in a different color, that are forced into the correspondingly shaped openings of the first layer. Clearly, one is able to avoid machining by adopting such a method, as the differently colored material is already exposed, though it is equally clear that a semi-finished article obtained will be polychrome on one side only; to produce color contrast on the remaining side, a third layer of metal must be employed, signifying an increase in gage and a considerable rise in costs, both of the end-product and of the various manufacturing operations necessary.
A further disadvantage of this particular process is that the shaped openings produced in the first layer are produced with the same machine as is used for applying contrast material to the second layer; this signifies that the added metal must of necessity be forced into the respective openings in order to snap into place.
Among the various drawbacks of both the processes outlined above, one has the need for a considerable number of operations to be carried out in preparation of the single metals, operations which are complex and do not always give precise results; what is more, the pairing together of the several layers is not always satisfactory.
It is important to note that all the prior are processes are characterized by the serious drawback of voluminous swarf, which is produced right through the process up to and including the end-product. Swarf is produced in such copious amounts because certain steps of the process, and certain types of end-products, dictate the punching and/or machining away of large amounts of material from almost all of the metals utilized. The production of large amounts of swarf, coupled with the necessity for refining, thus constitutes a problem of fundamental importance in the field of jewelry manufacture.